DERIVATIONAL • E-FREE TRANSLATION.COM • Definition of Derivational

... morphological elements in Japanese are of a different order than those in Latin. At times, such as when he describes the preterit subjunctive as agueta raba, his divisions fly in the face of derivational history. But he can claim a reasonable justification for his decision by citing Rodriguez' rule for the formation of this form; "add raba to the preterit of the verb" (Arte, 18v). Perhaps it is a prejudice founded upon familiarity with {9} contemporary ...

— Diego Collado's Grammar of the Japanese Language • Diego Collado